Aspergillus Section Fumigati Pneumonia and Oxalate Nephrosis in a Foal

Abstract

Equine pulmonary aspergillosis is a rare deep mycosis often due to the hematogenous spread of hyphae after gastrointestinal tract disease. We describe herein the main clinic-pathological findings observed in a foal, which spontaneously died after showing diarrhea and respiratory distress. Necropsy and histopathological investigations allowed to diagnose pulmonary aspergillosis, which likely developed after necrotic typhlitis-colitis. Biomolecular studies identified Aspergillus section Fumigati strain as the causative agent. Notably, severe oxalate nephrosis was concurrently observed. Occasionally, oxalate nephropathy can be a sequela of pulmonary aspergillosis in humans. The present case report suggests that the renal precipitation of oxalates can occur also in horses affected by pulmonary aspergillosis and could likely contribute to the fatal outcome of the disease.

Keywords: Aspergillus section Fumigati; horse; oxalate nephrosis; pulmonary aspergillosis.

Figure 1

Foal. Pulmonary nodule. Several fungi were present inside the alveolar lumina (a), within necrotic-hemorrhagic foci (b) as well as in the blood vessel wall (black asterisk indicates the lumen of the same vessel). In some microscopic fields (b,c), dichotomous branching hyphae were seen. Hematoxylin and eosin stain. Final magnification 400×.

Figure 2

Foal. Kidney. Typical fan-shaped, oxalate crystals were seen in the lumina of renal tubules, both in transverse (a) and longitudinal (b) section (black arrowheads). The precipitation of oxalates affected most of renal tubules (c, black arrowheads), which appeared distended, their epithelium being no longer detectable (a–c). Hematoxylin and eosin stain. Final magnification 400×.

Figure 3

Foal. Kidney. At very low magnification, the precipitation of countless oxalate crystals was evident (a). At higher magnification, the typical birefringence, with radiating spokes, could be appreciated (b). Polarized light microscopy, hematoxylin and eosin stain. Final magnification 25× (a), 400× (b).